(i) Field of the Invention
This invention relates to cyclone separators.
(ii) Prior Art
U.S. Pat. No. 4,237,006 (Colman et al) describes a cyclone separator having a separating chamber having first second and third contiguous cylindrical portions arranged in that order, the first cylindrical portion being of greater diameter than the second cylindrical portion and the third cylindrical portion being of lesser diameter than the second cylindrical portion, the first cylindrical portion having an overflow outlet at the end thereof opposite to said second cylindrical portion and a plurality of tangentially directed feed inlets, the separator being adapted to separate liquids one from the other in a mixture when infed into said separating chamber via said feed inlets, one said liquid emerging from said overflow outlet and the other emerging from the end of said third cylindrical portion remote from said first cylindrical portion.
The above separator is intended specifically, but not exclusively, for separating oil from water, the oil in use emerging from the overflow outlet and the water from said third cylindrical portion.
The aforementioned cylindrical portions may not be truly cylindrical, in the sense that they do not need in all cases to present a side surface which is linear in cross-section and parallel to the axis thereof. For example, U.S. Pat. No. 4,237,006 describes arrangements wherein the first cylindrical portion has a frustoconical section adjacent the second cylindrical portion and which provides a taper between the largest diameter of the first cylindrical portion and the diameter of the second cylindrical portion where this meets the first cylindrical portion. Likewise, the aforementioned patent specification describes arrangements wherein a similar section of frustoconical form is provided to cause a tapering in the diameter of the second cylindrical portion from a largest diameter of the second cylindrical portion to the diameter of the third cylindrical portion. There is also described an arrangement wherein the second cylindrical portion exhibits a constant taper over its whole length.
A difficulty has been found in operating cyclone separators of the kind described in U.S. Pat. No. 4,237,006 in that proper and reliable separating action is not always achieved, and contamination of the heavier liquid component (that emerging from the aforementioned third cylindrical portion of the separator) with the lighter liquid component sometimes occurs. Another difficulty has been that the outlet for the lighter component will frequently become blocked by debris, thus interferring with operation of the separator.
In accordance with one aspect of the present invention there is provided a cyclone separator comprising elements designed, sized and arranged for treating a mixture of fluids and more particularly an oil/water mixture for separating a more dense component from a less dense component thereof, said separator comprising a separating chamber having a primary portion which has a greater cross-sectional diameter at one end than at its other end and further having an overflow outlet at said one end thereof and an underflow outlet at said other end; at least one tangentially directed feed inlet proximate to said one end, said separator further including means designed, sized and arranged for acting to preclude contamination of the more dense component emerging from the underflow outlet by the less dense component, said means having an inlet end downstream of said other end of said primary portion with respect to the direction of flow of said separated more dense component, and an outlet end, said means presenting a passageway for throughflow of the more dense component, the diameter of which passageway has a diameter at said outlet end thereof which is from 1/3 to 0.8 the diameter thereof at said inlet end thereof.
Preferably, the primary portion is of length which is at least ten times its diameter at the plane of the feed inlet. The means for precluding contamination may take several forms. For example, it may be comprised by a secondary portion of the separating chamber at the underflow outlet. In one arrangement, the primary portion may comprise a first cylindrical section and a second cylindrical section contiguous therewith the overflow outlet being disposed at an end of the first section remote from the second section. The second section may have the underflow outlet at an end thereof remote from the first section. In this arrangement, the means for precluding contamination may be comprised by a third section at the underflow outlet.
In another arrangement, the primary portion may comprise a frustoconical section and the means for precluding contamination be comprised by a secondary portion of the separating chamber at the underflow outlet. In yet another arrangement, the aforementioned means may include an outlet pipe extending from the underflow outlet, the outlet pipe preferably having a substantially constant diameter.
According to another aspect of the present invention there is provided a cyclone separator comprising elements designed, sized and arranged for treating a mixture of fluids for separating a more dense component from a less dense component thereof, said separator comprising a separating chamber having a primary portion which has a greater cross-sectional dimension at one end than at its other end and further having an overflow outlet at said end end thereof and an underflow outlet at said other end; at least one tangentially directed feed inlet proximate to said one end said overflow outlet being in the form of a stepped bore including: a first bore portion having a diameter of sufficient size to facilitate the preclusion of blocking therein, the first bore portion being adjacent said one end of said primary portion of said separating chamber and a second bore portion of lesser diameter than the first bore portion the diameter of the second bore portion being sufficiently large to permit continuous operation of the overflow outlet, the second bore portion being further from said one end of said primary portion.
According to a further aspect of the present invention there is provided a cyclone separator comprising elements designed, sized and arranged for treating a mixture of fluids for separating a more dense component from a less dense component thereof, said separator comprising a separating chamber having a primary portion which has a greater cross-sectional dimension at one end than at its other end and further having an overflow outlet at said other, end; at least tangentially directed feed outlet proximate to said one end said overflow outlet being in the form of a stepped bore including: a first bore portion having a diameter of sufficient size to facilitate the preclusion of blocking therein, the first bore portion being adjacent said one end of said primary portion of said separating chamber; and a second bore portion of lesser diameter than the first bore portion the diameter of the second bore portion being sufficiently large to permit continuous operation of the overflow outlet, the second bore portion being further from said one end of said primary portion, the separator having means designed, sized and arranged for acting to preclude contamination of the denser component emerging from said other end of said primary portion, said means comprising a constriction at said other end.
According to yet another aspect of the present invention there is provided a cylone separator comprising elements designed, sized and arranged for treating a mixture of fluids for separating a more dense component from a less dense component thereof, said separator having a separating chamber having a primary portion which has a greater cross-sectional dimension at one end thereof than at its other end and further having an overflow outlet at said one end and an underflow outlet at said other end; at least one tangentially directed feed inlet proximate to said one end said separator further including means designed, sized and arranged for acting to preclude contamination of the dense component emerging from said other end portion by said less dense component, said means comprising a constriction at the other end of the primary portion, said construction presenting a passageway for throughflow of said dense component, the cross-sectional dimension of which passageway decreases away from the said other end of said primary section to a dimension in the range 1/3 to 0.8 of the dimension of the passageway at the end of said constriction closest said other end of said primary portion; said overflow outlet being in the form of a stepped bore including a first bore portion having a dimension of sufficient size to facilitate the preclusion of blocking therein, the first bore portion being adjacent said one end; and a second bore portion of lesser dimension than the first bore portion, the dimension of the second bore portion being sufficiently large to permit continuous operation of the overflow outlet, the second bore portion being further from said primary portion.
Preferably, the overflow outlet is provided with means selectively operable to vary the cross-sectional area of said outlets for permitting clearing of a blockage when occurring in that outlets. Furthermore, flow sensitive means may be provided positioned and operable for detecting a decrease in flow through the outlets and for operating the area varying means for increasing the cross-sectional area for the clearing.
Preferably, the outlet is in the form of an outlet pipe and the cross-sectional area varying means comprises a mechanism including a portion of the wall of the pipe which is so movable as to open the side of the pipe to the exterior thereof. Preferably, the aforementioned portion is a side segment of the pipe which is movable outwardly away from the remainder of the pipe under influence of the mechanism.
The mechanism may include an electromagnet and the flow sensitive means operates to apply electric current to the electromagnet for effecting movement of the segment away from the remainder of the pipe on said detecting of decrease in flow.
In another arrangement, the pipe wall portion is pivotally movable away from the remainder of the pipe. In this form, the pipe wall portion is arranged to be subject, in use, to a bias towards a position effecting the opening of the side of the pipe, and the flow sensitive means is positioned to be normally acted upon directly by flow through the pipe to impart a force thereon which is directed against the outlet pipe wall portion to maintain it closed, the force, however, being reduced in the case of reduced flow through the pipe due to blockage whereby the aforementioned bias effects movement to open the side of the pipe. Preferably, the flow sensitive means comprises a pivotal lever having two arms extending from a location at which the lever is pivotal to the remainder of the pipe, one arm being formed with means in use subjected flow thereonto from the separator and the other engaging the pipe wall portion.
The stepped bore arrangement described above has several advantages. For example, it is believed to create secondary recirculating flows which can be used to advantage to reduce the blocking effects of the solids at the overflow outlet end. These recirculating flows are believed to tend to "sweep" the core area of the flow and cause any solids to be removed via the underflow end. Furthermore, the inclusion of a stepped bore arrangement has permitted more efficient deblocking devices (of the mechanical type) be employed. Without the stepped bore arrangement this particular zone is relatively congested and cumbersome. Finally, there has been found to be a reduction in cavitation erosion as a result of the stepped bore arrangement.